Skyworks India Backend Engineer Interview: Rounds, Questions and Preparation

What the job involves

Backend engineers in global tech companies build and maintain server-side systems that power web and mobile applications, APIs, and data pipelines. Day to day, they write clean, efficient code, design database schemas, debug production issues, and collaborate with frontend and DevOps teams to deliver reliable, scalable services. Freshers typically start with well-defined modules, code reviews, and gradual ownership of microservices or background jobs.

Role and technical knowledge

1. 1

   What happens when you type a URL into a browser and hit enter, from a backend perspective?

   Cover DNS resolution, TCP handshake, HTTP request/response, server-side routing, and database or cache lookups. Mention status codes and headers.

2. 2

   Explain the difference between SQL and NoSQL databases. When would you choose one over the other for a backend service?

   Discuss schema flexibility, ACID vs BASE, scaling patterns, and use cases like transactions vs high-volume logs. Give a concrete example.

3. 3

   How would you design a REST API for a simple e-commerce order service?

   Define resources (users, orders, items), HTTP methods, status codes, pagination, and idempotency for POST. Mention authentication and versioning.

4. 4

   What is a race condition in a backend system, and how can you prevent it?

   Explain shared resource access, use of locks, transactions, or optimistic concurrency. Give an example like inventory decrement.

Practical scenarios and coding

1. 5

   You have a list of log entries with timestamps and error codes. Write a function to find the top 3 most frequent error codes in the last hour.

   Clarify input format, use a hash map for counting, filter by time window, then sort or use a heap. Discuss time and space complexity.

2. 6

   A service you own starts returning 500 errors after a deployment. How do you debug it?

   Check logs, metrics, and recent changes. Roll back if needed, reproduce locally, and add monitoring. Mention communication with the team.

3. 7

   How would you optimize a slow SQL query that joins three large tables?

   Use EXPLAIN, add indexes on join columns, avoid SELECT *, consider denormalization or caching. Discuss trade-offs of each approach.

4. 8

   Write a function to detect if a linked list has a cycle. Explain your approach.

   Use Floyd's tortoise and hare algorithm. Walk through pointer movement and edge cases like empty list or single node.

System design and scalability

1. 9

   How would you design a URL shortener like bit.ly that handles millions of requests per day?

   Cover key generation (hashing or counter), database choice, caching, and redirection. Discuss read-heavy optimization and analytics.

2. 10

   What is caching, and where would you place a cache in a backend architecture?

   Explain client-side, CDN, application, and database caches. Mention eviction policies (LRU) and cache invalidation strategies.

3. 11

   How do you ensure your backend service is highly available and fault-tolerant?

   Discuss redundancy, load balancing, health checks, graceful degradation, and retries with exponential backoff. Mention monitoring and alerting.

4. 12

   Explain how a message queue like RabbitMQ or Kafka can be used in a backend system.

   Describe decoupling, asynchronous processing, and buffering. Give an example like order processing or email notifications, and mention delivery guarantees.

Behavioural and HR questions

1. 13

   Tell me about a time you worked in a team to solve a technical problem. What was your role?

   Use STAR format. Highlight your contribution, communication, and how you handled disagreements or blockers.

2. 14

   Why do you want to work as a backend engineer at a global tech company like Skyworks India?

   Connect your interest in scalable systems and backend logic to the company's domain. Mention specific technologies or projects you admire.

3. 15

   Describe a situation where you had to learn a new technology quickly for a project.

   Show self-learning ability, resourcefulness, and application of the new skill. Mention the outcome and what you would do differently.

4. 16

   Where do you see yourself in three years, and how does this role fit your goals?

   Align with growing into a dependable backend engineer, deepening system design skills, and contributing to larger modules. Avoid vague answers.